Measurement and prediction of enthalpies of combustion and formation of oxygen and nitrogen heterocycles

Enthalpies of combustion and formation are reported for six O-heterocyclic and four N-heterocyclic compounds in crystalline or liquid phases. By the use of estimated enthalpies of fusion and vaporisation, liquid and gas enthalpies of formation were derived and compared with values predicted directly by the NIST Structures and Properties program and by the Pedley method. The results are discussed in relation to ring strain energies and the strength and weaknesses of the predictive methods are compared.